Flotation agent and method op producing the same



UNITED STATES PATENT OFFICE.

RALPH E. SAYRE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO METALS RECOVERY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

FLOTATION AGENT AND METHOD OF PRODUCING THE SAME.

No Drawing.

To all whom it may concern-.-

Be it known that I, RALPH E. SAYRE, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny, State of Pennsylvania, have invented certain new and useful Improvements in Flotation Agents and Methods of Producing the Same; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in flotation agents for use in the concentration of minerals by flotation; and includes the flotation agents themselves as well as the method of producing them.

Thiourea compounds, such as thiocarbanilid, have remarkable selective or collecting properties when used as flotation agents, but they are low in, or even substantially devoid of, frothing qualities, so that, when used in the flotation of minerals, with ore pulps which do not inherently have frothing properties, it is important to add a flotation agent having good frothing qualities, to supplement the action of the thioureas. Moreover, thioureas themselves, owing to their non-oleaginous character and the degree of their insolubility, are rela tively difficult to distribute throughout the ore pulp with uniformity. This dissemination through the pulp can be promoted by dissolving them in suitable solvents, but the solubility of a thiourea, previously formed, in its solvent, is limited. Accordingly, when a thiourea is dissolved in a solventhaving good frothing qualities, its

, limited solubility in such solvents may make it'necessary to add a much greater amount of the solvent than is necessary or desirable, from the standpoint of froth production, in order to supply a suflicient amount of the dissolved thiourea.

The present invention is based upon the discovery that a greatly increased amount of thiourea, in proportion to the solvent having good frothing qualities, can be obtained by carrying out the process of pro duction of the thiourea in such solvent, so that there is directly produced a solution of thiourea and accompanying by-products in the solvent having good frothing qualities. I have further found that such impurities and by-products as are formed simultane- Speeification of Letters Patent.

Application filed January 31, 1921. Serial No. 441,514.

ously with the formation of the thiourea, when produced in this .way, are not prejudicial to the use of the resulting composition as a flotation agent, but that the various impurities appear rather to improve the flotation properties of the resulting composition.

According to the present'invention, I use a solvent having marked frothing qualities which does not undergo objectionable change during the treatment to which it is subjected, and I mix with or dissolve in this solvent the amino compound or compounds from which the thiourea or thioureas are to be produced, together with carbon bisulfide in proper amountfor the conversion of the amines into thioureas, preferably addlng a small amount of sulfur 'to' promote the reaction; and I then heat the resulting mixture to bring about the combination of the. amines with the carbon bisulfide to produce the thiocarbanilid or other thiourea or thioureas directly in solution in the solvent. By carrying out the process in this way, the amount of 'thiocarbanilid or thiourea which can be produced and held in solution can be made much larger than where ordinary thiocarbanilid, in an isolated and purified state, is dissolved in a solvent therefor.- This appearsto be due to the fact that crystallization takes place less readily from the complex mixtures which are produced in the manner described than from simple solutions. The carrying out of the process in the manner described also gives directly a composite flotation agent containing both the thiourea and the solvent having marked frothing the thiourea compounds, so that composite products can be obtained containing the valuable thiourea collecting or selective powerful frothing agent.

agents-dissolved in an amount of a solvent or solvents in approximately the desired proportions for good collecting or selective action and good frothing qualities without any considerable excess of frothing agent.

he solvent which I have found particularly advantageous for use .in the processv of the present invention and in making the compositions of the present invention are ketone condensation products such as result, for example, from the action of calcium carbide on acetone. The liquid reaction product thus produced contains a mixture of acetone condensation products, such as mesityl oxide, isophorone, etc., and is a This liquid is also well adapted for use as a solvent of the thioureacompounds and can be used to ad vantage according to the present invention;

hibiting the tendency of the 'thiocarbanilid to separate or crystallize from solution. It seems probable that some reaction also takes place between the carbon bisulfide or the hydrogen sulfide and certain of the acetone condensation products, yielding compounds which further inhibit the separation of the thiocarbanilida These by-products, moreover, appeafto be advantageous in the composition produced, when used as a flotation agent, contributing to the flotation operation and supplementing the action of the thiocarbanilid and any unchanged acetone condensation products.

Insteadof using aniline alone, a mixture of amines can be added to the ketone condensation product solvent and reaction products of a varied and more complex character obtained and, in this case, it is possible to prepare stable solutions contain ing even larger amounts of thioureas than in the case of thiocarbanilid alone.

The operation of converting the amines into thioureas by the action of carbon bisulfidecan be carriedout in a very simple man ner. The proper amounts of the amines and the condensation'products can thus be mixed with an amount of carbon bisulfide in excess of that'required to react with the amines,

and a minute quantity of sulfur added to accelerate the reaction, and the mixture boiled under a reflux condenser until the conversion of the amines into thioureas has been brought about. The unchanged carbon bisulfide can then be removed by distillation, leaving a product somewhat dark colored and rather viscous, and which may have a somewhat disagreeable odor.; The process will be further illustrated by the following specific example, the parts being by weight:

250 parts of a mixture of acetone condensation products obtained by the action of calcium carbide on acetone, 100 parts of aniline, 50 parts of o-toluidine, 50 parts of mixed xylidines, 200 parts of carbon bisulfide and 0.5 parts of sulfur are mixed and boiled for a period of several hours under a reflux condenser until the conversion of the others, that it can be added directly to the flotation pulp just before the pulp is sub- 'jected to the flotation operation, for 'example, in a Callow pneumatic cell, and the composition can be readily disseminated throughout the ore pulp without any particular difliculty, so that excellent results can be obtained without any appreciable delay after the flotation agent is added. Moreover, increased amounts of the thioureas can be introduced inthis way, as compared with the amounts of the solvents, so that, as above noted, the use of an excess of the powerful frothing agents, which form the solvent or solvents, can be avoided, and a properly balanced composition, having strong selec-.

tive or collecting properties, as well as good frothing qualities, can thus readily be obtained. As little as 0.2 pounds of'the composite flotation agent, per ton of ore (figured on the dry basis) have thus been found capable of satisfactory use in the flotation of a copper ore, such as the ore of the Utah Copper Company. a

I do not claim herein the process of flotation in which thiocarbanilid and other thioureas are employed, as this process is claimed in the prior U. S. Letters Patent No. 1364308, and more generically, in U. S. Letters Patent No. 1364307 nor do I claim herein the process of flotation in which ketone condensation products are employed,

as this forms the subject matter of a prior application, Serial No. 393,607, filed July 2, 1920; but the present invention relates to improvements in composite flotation agents, and to improvements in the methods of their production. The composite flotation agents, containing the thioureas, are well adapted for use in carrying out the processes of the aforementioned Patent No. 1864308, and, when ketone condensation products are utilized as a solvent, for carrying out the process of my said prior application, Serial No. 393,607.

I claim:

l. The method of producing a composite flotation agent, which comprises adding an amine and carbon bisulflde to a solvent having marked frothing qualities, and bringing about the combination of the amine and carbon bisulfide to produce a solution of a thiourea compound in such solvent, whereby a solution is produced which is available for use directly in the flotation of minerals.

2. The method of producing a composite flotation agent, which comprises adding an amine and carbon bisulflde to a solvent containing ketone condensation products, and bringing about the combination of the amine and carbon bisulflde to produce a solution of a thiourea compound in such solvent, whereby a solution is produced which is available for use directly in the'flotation of minerals.

8. The method of producing a composite flotation agent, which comprises adding an amine and carbon bisulfide to a solvent containing acetone condensation products, and bringing about the combination of the amine and carbon bisulflde to produce a solution of a thiourea compound in such solvent, whereby a solution is produced which is available for use directly in the flotation of minerals.

ing ketone condensation products and a thiourea compound produced therein.

7. A composite flotation agent comprising acetone condensation products and a thiourea compound produced therein.

8. A composite flotation agent comprising a solvent having marked frothing qualities and a plurality of thiourea compounds, one of which is thiocarbanilid.

9. A composite flotation agent comprising a solvent having marked frothing qualities and a plurality of thiourea compounds produced therein.

10. A composite flotation agent comprising ketone condensation products and a plurality of thiourea compounds produced therein from carbon bisulflde and a plurality of aromatic amines.

11. A composite flotation agent comprising acetone condensation products and a plurality of thiourea compounds produced therein.

12. A composite flotation agent comprising a solvent having marked frothing qualities and a plurality of thiourea compounds produced therein by the combination of carbon bisulfide with anilin and substituted anilin.

In testimony whereof Iaflix my signature:

RALPH E. SAYRE. 

